Multiple monitor wallaper

Hello! I currently have a 15" retina MBP with a 24" 1080p display as a second monitor. I would like to make a wallpaper that spans across both displays, with the bezels on each representing a break in the actual image. I am running into difficulties in making the image line up correctly across the displays.

Hello! I currently have a 15" retina MBP with a 24" 1080p display as a second monitor. I would like to make a wallpaper that spans across both displays, with the bezels on each representing a break in the actual image. I am running into difficulties in making the image line up correctly across the displays.

I was in your shoes a few years ago. The real trick is match the pixel density on each screen so that it really looks like each monitor is a window looking onto the scene. Some simple proportional math will help you with that. The effective pixel density of the retina display is (2880^2 + 1800^2)^(1/2)/15 = 226.4155 pixels per inch (ppi). The pixel density of the 24" display is (1920^2 + 1080^2)^(1/2)/24 = 91.7878 ppi.

You have to increase the size of the image you use on the 24" monitor to match the pixel density of the laptop screen. So the horizontal resolution of the image you need on the 24" monitor is 1920/91.7878*226.4155 = 4736. Similarly, the vertical resolution is 2664.

Now that you know the working pixel density (226.4155), you need to measure the width of the bezels in inches and then multiply by 226.4155 to know how much space in the image to allow for them. For example, if each bezel is 1/2-inch wide, then you have one inch or 226 pixels of gap between your images.

Now, use your favorite image editor that supports layers to make some boxes of the right pixel sizes to represent your laptop screen, the external monitor, and the bezels. Arrange these boxes on top of a large image for the wallpaper and save out the two images you will need for the wallpaper: one image for each display. This will allow the images to line up on both monitors. In your case, you will need a starting image of 2880 + 226 + 4736 = 7842 pixels wide and 2664 pixels tall.

--- Post Merged, Aug 7, 2016 ---

By the way, here is a link to some very large images you can get started with. http://osxdaily.com/2013/02/15/12-stunning-high-resolution-wallpapers/ If you already have images you want to do this with that are not large enough for full retina resolution, then divide your working pixel density in half (113.2078) and use the effective resolution of the retina display (1440x900) for your image size calculations.

Thank you for the tips!! When I return to the US, I will give this a shot. I'm not really keen on paying for something that I can do with a bit of work myself, but it's good to know that it's there if I need it.

I was in your shoes a few years ago. The real trick is match the pixel density on each screen so that it really looks like each monitor is a window looking onto the scene. Some simple proportional math will help you with that. The effective pixel density of the retina display is (2880^2 + 1800^2)^(1/2)/15 = 226.4155 pixels per inch (ppi). The pixel density of the 24" display is (1920^2 + 1080^2)^(1/2)/24 = 91.7878 ppi.

You have to increase the size of the image you use on the 24" monitor to match the pixel density of the laptop screen. So the horizontal resolution of the image you need on the 24" monitor is 1920/91.7878*226.4155 = 4736. Similarly, the vertical resolution is 2664.

Now that you know the working pixel density (226.4155), you need to measure the width of the bezels in inches and then multiply by 226.4155 to know how much space in the image to allow for them. For example, if each bezel is 1/2-inch wide, then you have one inch or 226 pixels of gap between your images.

Now, use your favorite image editor that supports layers to make some boxes of the right pixel sizes to represent your laptop screen, the external monitor, and the bezels. Arrange these boxes on top of a large image for the wallpaper and save out the two images you will need for the wallpaper: one image for each display. This will allow the images to line up on both monitors. In your case, you will need a starting image of 2880 + 226 + 4736 = 7842 pixels wide and 2664 pixels tall.

--- Post Merged, Aug 7, 2016 ---

By the way, here is a link to some very large images you can get started with. http://osxdaily.com/2013/02/15/12-stunning-high-resolution-wallpapers/ If you already have images you want to do this with that are not large enough for full retina resolution, then divide your working pixel density in half (113.2078) and use the effective resolution of the retina display (1440x900) for your image size calculations.

Click to expand...

I'm trying to workout how to do this for my new iMac 27" 2017 & a AOC i2369vm. The iMac is 5120x2880 & the AOC 23" is 1920x1080.

I'm looking to use Photoshop to do this and have tried but can't seem to calculate sizes properly and the AOC 23" screen background comes out completely wrong.

if possible I would really appreciate your help with this as Maths isn't my strong point

I've worked out the first part but regarding layers and sizing everything correctly in Photoshop I'm having difficulty as I hardly use it. My starting image is larger than the 9698x2453 it needs to be but trying to work out the size I need layers and size of bezel to go on top of the image and then take those images I have no clue.

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